@book { KundenorientierungimSport,
    title = "Kundenorientierung im Sport",
    author = "Peter {Ewig} and Eike {Schindler}",
    year = "2007",
    publisher = "GRIN Verlag",
    address = "München, Germany",
    doi = "10.3239/9783638607940",
    url = "https://www.hausarbeiten.de/document/69881"
}